We work on three projects. 1. E. coli Antimutators: An antimutagenic mutation in E. coli has been found. The mutant is temperature sensitive and has a lower mutation frequency for some mutations than the parent. The kinds of mutations affected are being studied. Other questions that will be studied are map position, protein affected, relationship to mutagens and extra chromosomal genes. 2. RNA polymerase II in E. coli: The relationship of RNA polymerase II to RNA polymerase I is being investigated by the isolation of rna-mutants. 3. T7 phage: Three new mutations in T7 are being studied. They are in different genes. All affect the interaction of T7 with cells containing various episomes.